Pipe joint seal



June 28, 1949. A. STONE 2,474,556

PIPE JOINT SEAL Filed' Nov., 2s, 1945 A "5 /07 ,4 @Troy/MEX Patented June 28, 1949 UNITED STATES PATENT y OFFICE einen L. stfErlsnzri-:allstaa -I Application November 23, 1945, Serial No. 630,196'

2 Claims. (Cl. 285-154) )therwise interfering with the normal or desired {tructural requirements ofthe joint.

The invention has been developed especially for ;ealing threaded well pipe joints, particularly :asing joints, and as will hereinafter appear. ern- )odies and takes into consideration various fea- ;ures and requirements of casing joints. Aczordingly, the invention will be described particuarly, though typically in certain general aspects, Ls embodied in that kind of threaded joint.

Heretofore it has been proposed to seal well )ipe and other joints by the use of annular de- 'ormable sealing elements or materials, either reformed or put into the joint in iiuld condiion, and intended to eiect the seal by presenting un annular 'barrier to uids tending to leak hrough the threads. In some instances the seal las been located beyond the threads, while other `xpedients contemplate inserting the seal in the nterengaged thread area o the joint.

A general practice thus has been to present a leformable ring barrier against an annular-side f which uid pressure is exerted to press the seal material against the side or sides of the threads. md in adapting the joint for the seal, one of the ointvsections has been weakened to provide an ,nnular recess to accommodate the seal annulus.

In accordance withthe invention, the joint seal s effected on a diierent principle making possible las reduction to a simple and practicable form lhich -obviates the usual weakening of the joint tructure. It is found that an edective seal can `e maintained by presenting a localized dam ransversely across the thread course, as disinguished from a barrier coextensive with the nnular course of the threads. Accordingly, the nvention contemplates placing within one seclon and the interengaging thread area of the uint, an insert of suitable deformable sealing iaterial, such as any of the soft sealingv metals, lastics or rubbers, which fully occupies all spaces hat may exist between the threads at that localon and therefore presents a iiuid tight dam cross the spiral course of such. spaces.

Particular consideration has been given the pplicability of the seal to standard API, V-thread fell casing joints which as commonly made up, ontain owable sealingv compounds intended to iinimize fluid leakage through the joint,under he commonly encountered high pressures by lling clearance spaces beyond the thread crests nd any spaces that may exist between the anks fthe threads. One particular function of the resent sealing dam is to present a barrier against displacement of the sealing compound through the thread clearances and thereby enable the joint to retain the maximum quantity and extent of the sealing compound. In this connection it is particularly contemplated according to a preferred w of the threads, leaving the compound within the major course of the thread clearances.

l Further details of the invention and more complete understanding of the aforementioned features and objects will be had from the following w description of certain illustrative embodiments shown by the accompanying drawing, in which:

Fig. 1 is an exterior view intended to illustrate a standard API, V-thread casing joint;

Fig. 2 is an enlarged cross-section on line 2--2 of Fig. l;

gg illustrating the thread clearance; and

Figs. 5, 6, and 7 are views similar to Fig. 3, t illustrating variational forms of the invention.l

Referring rst to the general view of Fig. 1, the joint assembly comprises the casing sections g@ iii interconnected by the coupling il at the threaded joints I2. The connections may be standard API tapered V-thread joints formed, see Fig. 3, by a tapered course. of V-threads i3 on each pin end Illa of the casing, and corresponding threads in each box end lia of the coupling. The

thread shape is illustrated more particularly in. Fig. 4. Here it will be observed that because of practical considerations in the formation of the threads, clearances exist at Id beyond the thread crest and forming spiral channels through which fluid leakage may occur under the influence of pressures inside or outside the casing, the course of the leakage tendency therefor being from right to left in the joint sections shown in Figs. 3 to 7.

Imperfections in the thread formation and joint `make up may at times leave clearances between the thread ank surfaces I5, thus forming additional channels through which leakage may occur. As previously indicated, it is present practice to place on the threads before the joint is made up,

iiow resistant sealing compounds intended to I ill all spaces presented by the thread clearances and thereby seal the joint. However, at the higher internal pressures the sealing compound frequently is forced out of the joint through the clearance channels, permitting eroding duid leakage which in time weakens and opens the joint to excessive leakage.

The invention contemplates insertion within a localized and preferably small circular recess atteste within the interengaging thread area of one of the joint sections Ia or lla of a deformable seal which, as previously explained, forms a dam across the leakage channel or channels. ln accordance with the preferred form of the invention shown in Fig. 3, a body l of the sealing material is inserted within a closed end circular recess I1 within the inner or pin section Illa. Preferably the seallng material l is bonded to the metallic wall of the recess il as for example by vulcanizing a rubber insert directly to the metal. lt will be observed that the seal insert is most conveniently accommodated within the pin section ita since the surface of the latter is more directly accessible for drilling the recess and inserting the seal.

In its formation and placement within the recess, the seal insert i6 may be set into the pipe in substantially the form of a cylindrical plug, the outer surface of which projects just slightly beyond the crest oi the pin threads it, or a distance such that thereafter the seal material will fully occupy the channels i4 in the box end ila. Thread segments then may be cut or otherwise formed inthe outer face of the seal for alined engagement with the box section threads, the size of the thread segments on the seal being sulicient to assure complete closure of any leakage channels between the threads.l It will `ice observed that in Fig. 3 the seal is located within and near the ends ofthe threads last to interengage as the joint is made up. Accordingly, with the joint spaces It filled with the sealing compound, the seal I6 wipes and displaces the compound from only a small extent of the total interengaging thread course as the sections are screwed together, leaving the spaces I4 completely lled with the compound throughoutl the spiral course of the threads from the seal I6 to the inner end I8 of the joint. Tendency for fluid leakage out through the joint thus is effectively resisted by the presence of the sealing compound and the darn which the seal I5 places across the channels I4 to arrest any flow of the sealing compound.

In lig. e the seal. it composed and 'formed as previously described with reference to the seal cess in the outer joint section Il le. is will he understood, the seal may he placed at any desire; .location longitudinahy or the joint.

The-embodiment of Fig. ii is similar except that.

here the seal 2i is contained within a here extending radially through the wall of a coupling and ..ontaining a threaded plug which may be turned against the insert to `press and maintain it iiuid-tight engagement. with the pin threads. construction further permits insertion of the se ing element within the 'joint in made up con dition. The seal El may taire the iorrn or? a plug having thread segments formed on its inner face .in a manner corresponding to the sealing ele ment in Fig. 5, or it be extended as specincally illustrated to entend across and through tooth the pin and loon threads into a recess in the pin section, thus crrning a darn extending through the thread channels Hl and sealed at its ends and outside by pressed engagement with the plug te, the bottom of recess 2l, and the sides oi the bore and recess 2l. lThis form of seal may he preferred where high external pressures tend to produce fluid leakage from the outside of the casing through the joint. Ey making up or tightening the joint before insertion of the sealing element 2 l the aforementioned sealing compound.

shown to he handed within a circular remay be contained within the thread clearance throughout the entire extent of the threads. and under the circumstances, to particular benefit at the left or outside of the seal. By then applying the seal, the latter imposes a dam against displacement of the sealing compound occupying the full course of the thread clearances between the seal and the external thread run out. When the joint is to be broken, the sections may be un- SCIeWed, shearing oli the seal plug at the thread interface, a new seal to be inserted when the joint is again made up.

In Fig. the seal M is shown to be contained within a bore 2h extending radially through the inner section its and to be exposed at its inner end to the pressure inside the casing. The sealing element thus is rendered responsive to the internal fluid pressure, so that as the pressure increases the element is forced more tightly into sealing engagement with the `lcox section threads.

I claim: i

l. A threaded pipe joint comprising inner and outer sections having inter-engaging threads and spiral duid-containing clearance spaces beyond the crests of the threads that form fluidpassing channels containing a owable sealing substance, and a body of deformable material contained' within a recess in a portion only of the annular threaded area of one of the sections and having its inner face in sealing engagement with opposed threads and channels on the other section, said deformable material forming a dam across said channels so as to seal the joint against uid leakage therethrough and to crowd said owable sealing substance forward in said spaces as the sections are screwed together, the crowded ilowable sealing substance between the deformablev member and the inner end of the joint coacting with the deformable member to prevent uid leakage out through the Joint.

2. A threaded pipe joint comprising inner and outer sections having inter-engaging threads and spiral fluid-containing clearancespaces beyond the crests of the threads that form fluid-passing containing a ilowal sealing substance, and a ci" deformable material con-tained within a recess a portion only the annular threaded area ci one ofthe sections and having its inner race sealing engagement with op= posed threads channels on the other section, said deformable material seing nommetaliic and having elastic coalities and forming a (lam across said channels so as to seal the joint against huid ieaiage therethr ugh i to crowd said riowahle l sealing substance forward in seid spaces as the sections are screwed. together, the crowded ilowable sealing suestance between deformable 'member and the inner end oi joint enacting with the ltieferenable niemeer to prevent fluid leakage out through thejoint.

referencer are or record in the :File or Number Name Date 2,637,135 Dillon July i3, i937 2,179,202 Simpson Nov. 7, i939 FREIGN PATMTS Number Country Date 1,657 Denmark lune 13, 1898 

